Hearing Protection - Determining Need

OSHA's noise standard (29 CFR 1910.95) requires the use of hearing protection under the following circumstances:

• When the employee's noise exposure exceeds an 8-hour time-weighted average sound level (TWA) of 90 dBA (dose of 100%)
• When employees who have measured hearing loss (as prescribed by the OSHA standard) are exposed to an 8-hour TWA of 85 dBA (dose of 50%)

To determine if employees need hearing protection, employers must consider the following:

• The loudness of the noise as measured in decibels (dB) on the A-scale (dBA)
• The duration of each employee's exposure to the noise
• Whether employees move between work areas with different noise levels
• Whether noise is generated from one or multiple sources

Note that noise is measured with a noise dosimeter, which indicates daily noise dose in percent. OSHA provides a table titled Permissible Noise Exposures to determine the need for hearing protection. Here is this table.

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